I don't understand how the air permeability that you measured for the Rab Alpine Jacket (111 CFM) can be so off from the spec for the Pertex Equilibrium fabric that it is constructed of (~ 20 CFM). Any thoughts?

i think it just shows that unverified "specs" should be shoved down where the sun dont shine

this isnt climbing gear where specs need to be accurate for safety, or en-rated sleeping bags where EU rules require actual testing standards

quoted manufacturer specs can be wildly inaccurate ... and honestly much of the time have more to do with marketing mumbo jumbo

ive always found it quite funny personally when there are whole threads dedicated to arguing how this or that gear is better on paper according to the manufacturer specs, when you dont know if they are even accurate

also remember that a fabric that has seen usage can be quite different from when it is new

I was curious as to why the “coffee filter” air permeability tests that Wim Depondt conducted on a NEW RAB Alpine seemed to indicate comparable breathability to the RAB Boreas. Wlm Depondt tested approximately 75 CFM for both. My lab tests showed the RAB Boreas was 68.7 CFM but, the USED RAB Alpine tested 111 CFM.

I took multiple micrographs of both fabric sides of the USED RAB Alpine. The following micrographs are 5.0mm and 1.4mm Field of View clearly indicating that a very-thin-clear PU (VTC PU) coating was added to the inside of the fabric during manufacture:

There were no visible wear spots on the outside of the fabric to indicate abnormal use. Consequently, it is plausible that the NEW air permeability could have been comparable to the RAB BOREAS when new, but, degraded to the 111 CFM level, from the VTC PU coating reduction, with 20 - 25 days of normal use.

A VTC PU coating on the inside of the Gossamera fabric (Arcteryx Squamish) has been used by Arcteryx since the 2009 model year. My hypothesis may also apply to this garment.

I'd estimate that's I've worn the alpine 20-25 days since last winter, mostly back country skiing with a pack on. It might have gotten thrown in the wash & dwr'd with a couple other garments, but I'm not certain.

I would say that the first three (breathability, water resistance and weight) are the most important to me. Other factors are nice, and will play a part in my purchasing decision, but those three are by far the most important for me. For example, I care about durability, but own Propore (I just know they are fragile). I want to save money, but I've bought (and will continue to by) Cuben. If there is some magic windshirt that does well in all three categories, then I'll spend lots of money, even if is fragile.

With that in mind, I suggest a table with at least those three items. It can have more (your call). Along with that, I would make a chart with breathability on the X and water resistance on the Y (these can be swapped if you prefer). Then I would represent weight with a bubble (the bigger the bubble, the heavier it is). I think this would be fairly intuitive. For example, if you were displaying rain jackets, than an Event jacket shows up in the upper right quadrant (very breathable and water resistant). A Propore jacket is a little bit closer to the axes. But the Propore jacket has a much smaller circle. (I've used rain jackets for my examples, even though I know this is for comparing windshirts).

The other advantage of this approach is that you can draw a line to designate something. For example, you could have a line designate what is generally considered "waterproof". Beyond that, a lot of people won't care if a jacket is more water resistant. Likewise, a line for the 35 marker on CFM.

I don't think this has been done before because it's not necessary. If you want to display these four attributes, it's best to just list them out.

The most obvious problem is that the chart has lines that imply, for example, that an item has more water resistance as it gets lighter. From an engineers perspective, if a given line represents a given product, it implies that the product's attributes exist anywhere on that line. We know that this isn't true because all of the attributes shown are fixed, not functions of each other.

For bushwhacking in perpetually damp conditions, I have found the WT 1.0 fabric without equal. If a fabric doesn't test well for my intended purpose, I just get rid of the garment. If I keep it, then I inevitably find a few tailoring issues to moan and groan about. After that, I make the DIY tailoring changes to optimize the garment for my needs.

Tailoring Issue 1: Like you, I found the hood lacking. It’s only cut for "under helmet" applications and there are no options to adjust its volume or head position. To correct this, I always wear a wide brim hat with it; the hat has an internal adjustable head band size. It allows me to customize the WT 1.0 hood volume and position the way I want it and keep it in place under the hat.

Tailoring Issue 2: I want to close the wrist aperture when heat needs to be retained and loosen it up, along with the neck zip, to facilitate chimney effect cooling when needed. I rarely take off my pack to make clothing adjustments. I added Velcro wrist closures.

I received this response from Black Diamond:-----------------------Thanks for getting in touch with us. The jacket is 40 CFM (cubic feet per minute) which is technically 40 CFM/M2 (cubic feet per minute per meter squared) but the industry simply refers to this as CFM. This is testing done by Schoeller and tested by BD. It is a stretch fabric and should increase the CFM slightly when stretched.

The hydrostatic head is approx 500 mm. It is treated with Nanosphere but does not have any coating that is generally required to get higher hydrostatic performance.

The ASTM D737 standard on page 3 says, "11.1 Air Permeability, Individual Specimens—Calculate the air permeability of individual specimens using values read directly from the test instrument in SI units as cm3/s/cm2 and in inch-pound units as ft3/min/ft2, rounded to three significant digits."

Kim may have the English representations and the SI representations mixed up. If so, a 40 SI value equals a 78.74 CFM value. As a general rule, EU companies (Schoeller is Swiss) spec their values in SI format.